tag:techtv.mit.edu,:Array/233338720 2008-09-02 10:20:19 -0400 MIT Department of Physics Technical Services Group <p>A stuffed monkey is suspended from a rod at one end of a lecture hall by an electromagnet. A golf ball gun aimed directly at the monkey cuts power to the electromagnet when fired. Thus, the monkey begins falling at the same instant the gun fires the golf ball. The projectile and target meet in mid air.</p><p>Intuitively one might think that the ball will go over the monkey's head due to its fast speed. However, gravity accelerates all objects downward at the same rate, meaning the monkey and the ball will meet at exactly the same point. If the ball was shot even faster, it would still hit the monkey, but higher above the ground. </p><p>No animals were harmed in this demo. </p> 77 tag:techtv.mit.edu,:Array/233316460 2008-09-02 15:08:22 -0400 MIT Department of Physics Technical Services Group A pair of spinning wheels 1.5 meters apart is placed in the path of a bullet. A bullet is fired with the wheels stationary for reference position, and fired again with the wheels spinning at a known speed. The second wheel will rotate more than the first as the bullet crosses the gap between them. When the angles between the reference holes and the second holes are compared, the speed of the bullet can be determined. <br><br> The balloon is used to show when the bullet has passed through both disks. <br><br> This video was shot with a Phantom v7.1 high speed video camera (donated by Vision Research Inc.) at approximately 7000 frames per second. The frame data can be seen at the bottom of the screen. <br><br> Special thanks to Dr. Jim Bales, MIT Edgerton Center. 22